Hydraulic valve



Aug. 25, 1931. H. ERNST YDRAULIC VALVE Patented Aug. 19,31'` v iUNiTEDsTr mms iiaNsfr, or cmcmiwafrr, on'io, Assrenoa I comm, or vcmcmna'rr, onio,

A ooarom'rron or omozi; i;

' minnene' Vanvi,

I Application filed March 8,

This invention relates to hydraulic valves and plungers and moreparticularly'to improvements in valVes of the spool type.

One of the principal objects of thevpres'e'nt p grooves around theperipheryi. offthe Valve. j

Other objects and advantages of .the present invention should bevreadilyappare'nt by referring to the following specifieation consideredin conjunction with the accompanying drawings illustrative" of onevembodiment thereof and it is to be understood that any modifications maybe made in thev specific structural details liereinafter f'disclosedwithin the scope of the :appended claims without departing the spirit ofthe invention. 1

Referring to the drawings invswliich like reference 'numerals indicatelike parts-Figure 1 is a'sectional View of a Valve present- 4 v I p ifluid isflowingfaround the reducediportion ing one embodiment of thisinvention.

Figure 2 is a detail of the grooves formed in the Valve.

Figurel3 is a detail'showing'in exaggerated form the lateraldisplacement Vof a Valve caused by closing a high pressure port.,

Figure 4 is a section on' the line of Figure 1.

- One form or embodinient of this inventioii erence numeral 10 indicatesgenerally a Valve' casing. ina bore 11 of the casing and has a pluralityof longitudinally spaced pairs of diametrically Opposing ports 12 formedtherein. An annular groove or channel 23 which may be formed in'theperiphery of the bushing circumscribes and interconnects each pair ofthe ports as shown inFigure 3, which` anformed in the Valve bod Valvestructure adapted'to 'kage'takes place due to .sures existinginvariousparts'. of :the Valve. I from or exceeding g i w vpoint ofhighflpressu ple 5 of t hin 'the surface of 1 in which the ref-` Abushing 20 is permanently fixed-` 1930.- seriai'xe. Asya-via s v nulargroove'is also 'connected with, a port p p or casing and it is apparentthat ifthefva Ve body 'ressure one that the'` hydraulic medium wouldeiiter theannular groove and flow to both of the. ports 12cand thusenter a Valve 'chamber suchflas 18 from Opposingl .sides thereofLf. v

Con-Versely if the Valve body port was an 'exhau`st, the hydraulicmedium would leave the Valve chamber' from 'opposite sides lthrough theports 12 .and fiow by means of thev annular grooveto the exhaust port.The` portsare arrang'ed `'n this manner in order to geometricallybalance the forces acting on' the Valve 713 slidably` mounted in thebushing. V,

Valve-1,3 is v. composed. of a plurality of spools 14,14' and 14connected together by reduced portions 1.5. The Valve is adapted. -toslide back and vforth in its bushing to control the flow of thehydraulic medmin. In

the OperationH of this type of Valveit has been found that a certain'amount the difl'erenti'al pres- In' other fwofif'ds;4 leaka'geiwillfl'owjfr'om any nithe Valve to a con- Boine Qjfflowp is as'sume thatiguous k t v rthe 'port'17 is con'-, of high pressure and nected lto.la source;

of thevalve to'v the port 21, the'chamber 18 'would'thenz beunderflhighfpressure. lIf the' intervening spacejbetween one` of thelValve spools and'tlie bushing isat af lower pressure leakage 'willi'fio'w' these spaeesf` s s 4 s These r/spa'ces maybe due to imperfectionsthe Valve spool or the bushi'n or to the fact that the Valve maybeslightly displaced llaterally in its bushing as a result offa previousmovement. In either, case the fluid is forcibly spread. between one sideof the Valvespoolv and'the casing creating an unbalanced pressure onthat side ort was a ro rnncriwcmiu'rr urrtmemcnian s .of ieakessure. Assan exain-'- f fi`-`o`nfrth`er chamber 18 to etV 'I which will force theother side into sufliv cient frictional contact with the wall of thecasing as t'oimpede the; movement of the Valve. Again ifl the spool suchas 14 was in lao position to close a high pressure port and thereexisted a slight space between the Valve and its casing around the portorifice as a result of imperfection in the surface of the Valve -spoolor due to the Valve being slightly displaced laterally, the differentialpressure between the port and the intervening space would .cause thefluid to be forccd into that space or in other words leakage would takeplace for a certain undefined area around the orifice of the portbetween the Valve and its bushing. The leakage in this case would havethe additional effect of increasing the projected area of the spoolunder pressure thereby causing lateral movement of the Valve in itsbushing which is shown in exaggerated form in Figure 3. Once thiscondition arises the lateral movement of the Valve increases the spreadof leakage which in turn increases the projected area under pressurecausing further movement. It is thus seen that each of these factorsaggravates the other until the Valve is finally pressed into such greatfrictional contact with one side Valve will stick, to move it.

In order to control this leakage and at the same time overcome thisunbalancing effect of a high pressure port there is provided in theperiphery of the Valve spools a plurality of small annular grooves 16shown more particularly in Figure 2 which are closely spaced together.In other words the smooth surface of the Valve spools is broken up asmuch as possible. by these small grooves, the efl'ect of Which istwofold. They tend to break up the spread of leakage while at the sametime create rings of pressure around the Valve which .act as a centeringand balaneing means.

In breaking up the leakage flow the following action takes place.

Assuming that the chamber 18 is full of high pressure fluid any leakagetherefrom must flow between the Valve spools and the casing. This flowwill spread in any given directionl until it meets the first groove inthe spool.

The groove would then lead the fluid about the spool before any otherleakage would take place. At the completion of this fluid movement aring of equalized fluid pressure would be formed around the spool asshown in Figure 4 which would be limited by the size of the groove.Since the pressure in .this fluid ring is equal at all oints it reducesthe tendency of the fluid to reak out at any particular point and leakto the next groove. In this manner the leakage is broken up anddiminished.

The function of the grooves in aiding to overcome the unbalancedpressure on the 1Valve from a high pressure port is as folows:

of the bushing that the making it almost impossible 'a Valve having aplurality Taking the port 17 again as an example if the Valve spool 14is in a position to shut off communication therefrom the grooves whichare exposed to the port pressure will lead the fluid in spaced annularpaths around the Valve with the result that the leakage is confined todefinite annular lines irrespective of how far the leakage may flow toeither side of the port. In other words the grooves translate theleakage into annular rings of pressure thus insuring that the pressureon the periphery of the Valve is equal at all points. It is thusapp-arent that the grooves prevent the formation of uncontrolled leakageareas between one side of the Valve and its bushing with theirunbalancing effect on the Valve and also that they aid in overcoming theunbalancing effect of a high pressure port, a1l of which prevents theValve from binding or sticking in its bushing and roduces a freelymovable Valve suitable or high pressure work.

Attention is invited to the fact that Valves of the above type whichhave no intermediate reduced portions are known as plunger valves and itis contemplated within the scope of this invention that such valves maybe provided with small annular grooves for the purpose of preventing thecreation of uncontrolled leakage areas and thus provide a freely movableValve.

What is claimed is:

1. In combination with a Valve casing,

of spools consaid spools havgrooves longinected by reduced portions, inga plurality of annular tudinally spaced therealong.

2. In a Valve casing having a plurality of ports, a Valve member havingpiston-like portions adapted to open and. close said ports said portionshaving means thereon to cause an annular flow in a cross direction to aleakage flow to prevent the establishment of unbalanced forces on theValve.

3. In combination with a Valve casing having a plurality of ports, aValve slidably mounted therein and having a plurality of piston-likeportions connected by reduced portions, said reduced portions adapted topermit flow from a pressure port to an outlet port and means on thepiston-like portions to retard leakage of said flow comprising aplurality of annular grooves longitudinally spaced on the periphery ofthe last named portions.

4. In combination with a Valve body having' a pair of Opposing ports, aValve member for-opening and closing said ports, said Valve memberhaving means thereon to cause substantial equalization of the Opposingvport pressures on the Valve when in closed position.

l5. In a device of the class described, a i

body member having a plurality of fluid 4 or from channels therein, eachchannel communicating with a pairvof opposed ports communicating with abore of the body member, a Valve element mounted n said bore comprisinga plurality of piston-like portions connected by reduced portions, and aplurality of relatively small annular groovesl closely spacedlongitudinally of the first named portions whereby the leakage from ahigh pressure port when said port is closed the chamber around thereduced portions when said port is open will be prevented fromlocalizing on one side of the Valve and causing an unbalanced conditiontheren. v

In testimony whereof I aflix my signature.

HANS ERNST.

